Fixed flooring division by a power of 2, once again...

src/x64/lithium-codegen-x64.cc

Index: src/x64/lithium-codegen-x64.cc
diff --git a/src/x64/lithium-codegen-x64.cc b/src/x64/lithium-codegen-x64.cc
index 41321340e01ca4e302e91291bc54e864e47ee647..809df5d9327435b1022b2bd48a85510f9eccf75f 100644
--- a/src/x64/lithium-codegen-x64.cc
+++ b/src/x64/lithium-codegen-x64.cc
@@ -1134,16 +1134,17 @@ void LCodeGen::DoFlooringDivByPowerOf2I(LFlooringDivByPowerOf2I* instr) {
     DeoptimizeIf(zero, instr->environment());
   }
 
-  // If the negation could not overflow, simply shifting is OK.
-  if (!instr->hydrogen()->CheckFlag(HValue::kLeftCanBeMinInt)) {
-    __ sarl(dividend, Immediate(shift));
+  // Dividing by -1 is basically negation, unless we overflow.
+  if (divisor == -1) {
+    if (instr->hydrogen()->CheckFlag(HValue::kLeftCanBeMinInt)) {
+      DeoptimizeIf(overflow, instr->environment());
+    }
     return;
   }
 
-  // Note that we could emit branch-free code, but that would need one more
-  // register.
-  if (divisor == -1) {
-    DeoptimizeIf(overflow, instr->environment());
+  // If the negation could not overflow, simply shifting is OK.
+  if (!instr->hydrogen()->CheckFlag(HValue::kLeftCanBeMinInt)) {
+    __ sarl(dividend, Immediate(shift));
     return;
   }